The present invention generally relates to a storage system and its control method, and in particular can be suitably applied to a storage system that controls a storage controller based on access information from a host system.
Recently, in storage systems that handle vast amounts of data, a storage controller is used for controlling the input and output of data to and from the host system in order to store large-capacity data sent from the host system.
A storage controller has a logical volume (hereinafter referred to as a “logical volume”) formed on a physical storage area provided by a plurality of hard disk devices configured to be operated according to a RAID (Redundant Array of Independent Inexpensive Disks) system.
The storage controller performs data processing according to the access pattern information of a read/write request received from the host system.
In relation to the above, disclosed is technology for improving the performance of the overall storage system by increasing the processing speed of data to be performed by the storage controller that received the read/write request.
Japanese Patent Laid-Open Publication No. H10-240450 discloses technology of alleviating the deterioration in the system performance by storing data of low access frequency in an internal storage apparatus even when it is flushed from a cache memory when handling data of a plurality of access patterns in a single cache memory.
Japanese Patent Laid-Open Publication No. H11-212733 discloses technology of alleviating the deterioration in the system performance by a controller controlling a magnetic disk providing information concerning a logical volume to a storage controller, and allocating the cache memory to be prefetched by the storage controller to each logical volume.
Japanese Patent Laid-Open Publication No. 2003-131814 discloses technology of alleviating the deterioration in the system performance by a storage controller allocating its resources based on the characteristics of the access pattern from a host system.
Specification of Japanese Patent Application No. 2006-304526 describes that it is possible to alleviate the deterioration in the system performance by calculating the performance load of a logical volume according to the access pattern from a host system, and rearranging the target volume to be subject to performance load balancing to different RAID groups.